US3494375A - Hydraulic fuse with plural flow paths - Google Patents

Description

Feb. 10, 1970 J. 5. HENAUGHAN HYDRAULIC FUSE WITH PLURALPLOW PATHS Filed June 29, 1967 S. Heno ughan MM. M

I {I I ATTORNEYS United States Patent 3,494,375 HYDRAULIC FUSE WITH PLURAL FLOW PATHS John S. Henaughan, Rolling Meadows, Ill., assignor to Componetrol, Inc., a corporation of Illinois Filed June 29, 1967, Ser. No. 650,034 Int. Cl. F161: 17/08, 35/12, 21/04 U.S. Cl. 137599 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to so-called fuses for altering or interrupting fluid flow, and particularly to metering fuses designed to operate after a predetermined volume of flow. Among other objects, the invention aims to provide means for overriding the operation of a metering mechanism particularly with respect to the limiting of a predetermined volume of flow. In other words, the invention permits the temporary passage of an unlimited amount of fluid through the fuse whenever circumstances make this desirable.

The nature of the invention and other objects and advantages thereof may be readily understood by reference to illustrative fuses adapted for metering low rates of flow and shown in the drawing.

In said drawing:

FIGURE 1 is a longitudinal section of a fuse constructed in accordance with the teachings of this invention, and;

FIGURE 2 is a fragmentary end view of an upper portion of the device shown in FIGURE 1 as viewed from the right-hand side.

This invention is an improvement over the type of metering fuse disclosed in U.S. Patent No. 2,592,486, issued to Donald A. Stark and U.S. Patent No. 2,772, 065, granted to William W. Thomas.

It will be apparent that the principle of the invention is not limited to these types of fuses.

In fuses of the type to which the invention is shown applied, the metering valve mechanism of the fuse operates to alter the fluid flow (in this case out off the flow) after a predetermined volume of flow has passed through the line regardless of the pressures involved, or the variation in viscosity of the fluid. As soon as flow starts a valve element starts to move towards its seat which it reaches after a predetermined volume of flow. Fuses of this type protect against excessive loss of fluid in the event of line breakage; they permit such volume of fluid to flow (preferably a slight additional amount as a safety factor) as is required to operate a particular instrumentality, such as a piston, and close the line (to prevent further loss) if the flow exceeds this amount, as would be the case under abnormal situations, such as fracture of the line or excessive leakage from Whatever cause.

3,494,375 Patented Feb. 10, 1970 However, proper operation of fluid circuits in which fuses of this type are employed usually require that the fluid line leading up to, and including, the load or other instrumentality connected in the circuit be purged of any air, or other gas, which would vitiate the effectiveness of the incompressible hydraulic fluid employed as, for example, in hydraulic brakes system. This means that before the system can be made ready for operation the entire line must be bled of air, or other gases and, to accomplish this an amount of fluid must be passed through the line which normally would greatly exceed the volume which the hydraulic fuse will allow to pass without automatically closing the line.

In the past it has been customary to circumvent the operation of such fuses by the attachment of an auxiliary tubing connected adjacent the inlet and outlet of the fuse to provide a bypass thereof. It will be recognized that this is more or less of an expedient and that the necessary provision of additional fittings for attaching and disconnecting the bypass conduit introduces additional factors contributing toward possible failure of the system and that the necessary removal of the bypass means always provides for the possibility of inadvertent introduction of air into the hydraulic line.

It is therefore an object of this invention to provide hydraulic fuse means wherein there is combined metering valve means for limiting the volume of flow of fluid into an instrumentality supplied from a source of fluid together with means having external actuating means for circumventing the metering valve means to permit an unlimited flow of fluid through the system when desired.

In accomplishing the objects of this invention, provision is made in a hydraulic fuse means for two parallel fluid paths from the inlet to the outlet of the fuse, one of these paths being normally closed, the other path containing metering valve means normallyintended to shut off the flow of fluid through that path after a predetermined volume of fluid has passed therethrough; the first of the aforementioned fluid paths including externally operable valve means permitting unobstructed flow of fluid from the inlet to the outlet of the fuse regardless of the conditions in the second of the two fluid paths.

In the drawings there is shown a preferred form in which the invention may be practiced in which the fuse means comprising a housing, generally indicated by numeral 10, which housing may comprise a main housing 11 and "an auxiliary housing 12 preferably formed integrally therewith. The main housing, which may be generally elongated in shape, includes inlet orifice means 13 at one end for connection with conduit means (not shown) leading to a supply of fluid under pressure, and outlet orifice means 14 at the other end of connection with an instrumentality, or load, (not shown) to be supplied with fluid from the fluid source under the control of the fuse means.

The interior of the housing 11 is generally cylindrical in cross-section and contains a generally cylindrical hollow shell 15 extending substantially the entire length of the interior of the housing and of less diameter than the interior thereof to provide an annular chamber, indicated by numeral 16, at the inlet end of the housing and another annular chamber 17 adjacent the outlet end of the housing, these chambers being separated from each other by a radially outwardly extending flange portion 18 of the shell which may include seal means such as the resilient O-ring 19.

Communications between the inlet 13 and the annular chamber 16 is established by means of one or more generally radially extending passages 20- and communication between chamber 16 and the interior of the shell 15 is established by means of a series of circumferentially spaced ports 21. Similarly, communication between the interior of the shell and the annular chamber 17 is established by means of the circumferential ports 22, and the chamber 17, in turn, is in communication with the outlet 14 through radial passages 23.

Contained within the shell 15, adjacent the inlet end of the housing, is a slidable poppet piston 24 having at one end a generally conically shaped valve surface 25 which, upon movement of the poppet towards the right as viewed in FIGURE 1, is engageable with an inwardly directed constricted portion of the shell forming a valve seat 26 formed within the shell intermediate the ports 21 and 22. It will be evident therefore that the two annular chambers 16 and 17 may be placed in communication with each other through the interior of shell 15 by means of the respective ports 21 and 22, and in communication, respectively, with the inlet 13 and outlet 14 by means of the passages 20 and 23.

Within the cylindrical shell member 15 at the inlet end of the housing there is formed a small internal chamber 28 which is in communication with the annular chamber 16 and port 20 by means of one or more radial ports 27. This small chamber is provided with an axially extending passage 29 for establishing communication between the chamber 28 and the left hand side of a poppet piston, 24, the flow of fluid through the passage 29 being under the control of a check valve 30 which, in turn, is provided with a relatively small central orifice 31. This check valve is arranged so that substantially unrestricted flow of fluid through the passage 29 is 'permitted in a direction leading from the interior of the shell 15, through the chamber 28, port 27 and to inlet 13 through the annular chamber 16, while only a relatively small rate of flow of fluid is permitted to enter the interior of the shell 15 under the influence of fluid supplied under pressure to inlet 13 of the fuse means.

The size of the orifice 31 is chosen so as to establish a predetermined ratio between the amount of fluid flowing into the shell 15 behind (to the left of) the poppet piston and the rate of flow of fluid flowing into the interior of the shell through port 21 in front of (to the right of) the poppet piston. It will thus be seen that, regardless of the temperature or viscosity of the fluid entering the inlet 13 under pressure, so long as a continuous flow is maintained there will be a continuous movement of the poppet piston 24 towards the right until such time as a predetermined amount of such flow causes the poppet to stop the flow of fluid by contact with the valve seat 26. On the other hand, whenever the pressure differential within the fuse means is such that liquid flows in a direction from the outlet 14 towards inlet 13, check valve 30 will become unseated to allow substantially unrestricted flow of fluid through the passage 29, chamber 28 and ports 27 and 20 so that the poppet piston will return to its starting position (as shown in the drawing) almost immediately.

When the fluid system is at rest the poppet piston 24 is restored to, and maintained in, a position at the extreme left-hand end of the shell 15 by instrumentalities which will now be described. These include a hollow piston means, indicated generally by numeral 32 having a skirt portion 33 slidably received within the right-hand portion of the shell 15 with a cylindrical extension portion 34, of substantially reduced external diameter, terminating with a closed head portion 35 at its left-hand end. Within the interior of the piston 32 there is provided an inwardly directed flange portion 36 which serves as an abutment for one end of a biasing means, such as the coil spring 37, the other end of the spring abutting against the right-hand end wall 38 of the shell thus normally urging the piston 32 in a direction tending to bring its extension portion into abutting engagement with the poppet piston 24 and (assuming there is no flow of fluid opposing this movement) to urge and maintain the poppet piston in its starting position.

Contained within the extension portion 34 is a check piston 39, provided with biasing means, such as the coil spring 40, tending to urge the check piston in a direction towards the right into engagement with one side of the flanged portion 36 which serves as a valve seat for the check piston. The closed end of the check piston, however, may be provided with a small orifice 41 whereby a small amount of fluid may be allowed to leak past the valve, if desired. Communication between the interior of the shell 15 and the interior of the extension portion 34 is accomplished by means of a series of radial ports 42 at one end of the extension and another series of radial ports 43 at the other end of the extension portion, these latter ports being normally closed by the check piston 39 when it is in its closed position. It should also be noted that under conditions of static pressure, as shown in the drawing, the skirt portion 33 is disposed to the left of the ports 22 so as to effectively shut off communication between the annular chamber 17 and annular chamber 16. However, as soon as pressure is supplied to the fluid in chamber 16 fluid will flow through the port 21, the annular space surrounding extension 34 and into the extension through ports 42 to build up pressure behind the rear face of check piston 39 to move the piston 32 as a unit towards the right to uncover port 22 and, so long as pressure is being supplied at the inlet to the fuse means, fluid will thus pass into the annular chamber 17, through ports 23 and to the outlet 14. This combination of ports, passages and chambers comprises a main path for the flow of fluid through the fuse means. on the other hand, as soon as the flow of fluid has been stopped, and no pressure differential exists between the inlet and outlet of the apparatus, the piston 32, under the influence of spring 37 will return the poppet piston 24 to its starting position.

Finally, if a condition exists such that the pressure is greater at the outlet 14 (such as would be the case when the pressure at the fluid supply has been reduced and the actuating mechanism, or load means, is returning fluid to the source of supply) the fluid entering the outlet port 14 may bypass ports 23 and 22 and pass directly through the center of shell 15, forcing check piston 39 against the force of spring 40 to uncover ports 43 thus permitting substantially unrestricted return flow of liquid through ports 21, annular chamber 16 and ports 20 to the inlet 13.

All of the foregoing elements, or their equivalents, have been described and claimed in the above-mentioned US. patents granted to Stark, No. 2,592,486, and Thomas, No. 2,772,065, and are not being claimed per se in the present application.

The improvements over past devices of this type include the instrumentalities contained with'the auxiliary housing 12 which is preferably formed as an integral extension of one side of the main housing 11. This housing includes a pair of spaced passages 44 and 45 which extend inwardly through the'main housing to intersect the interior therewith in communication respectively with those portions of the interior which comprise the chambers 16 and 17. These passages may conveniently be formed by drilling spaced bores from an exterior fiat surface 46 of the auxiliary housing the outer ends of these passages being countenbored, as at 47, and closed off by means of removable sealing means such as the plugs 48, these plugs being removably contained within their respective counterbores by means of a flat plate 49, secured by a cap screw 50. The auxiliary housing is also bored in a direction transverse to passages 44 and 45 to provide a communicating passageway 51. This passage may also be counterbored at one end to provide an annular seat 52 for the conical surface of a poppet valve 53 having a fluted stem 54 slidably received within the passage 51 and extending into a chamber 55 provided by drilling into the auxiliary housing from the other side to provide communication be tween the passages 45 and 51. The counterbored portion of the auxiliary housing which provides for the valve seat 52 may also be threaded at its outer end 56 for removably receiving a cup-shaped plug 57, this plug serving to anchor one end of a coil spring 58 which encircles the rearward end of poppet 53 having its other end in engagement with a flanged portion of the poppet to normally urge the poppet into engagement with the valve seat 52.

The open end of chamber 55 is closed by means of a plug 59 provided with appropriate sealing means, such as resilient O-ring 60 and backup ring 61, the plug being removably secured in place by means of cap screws 62. The plug itself is provided with a central :bore 63 for slidably receiving the stem 64 of an actuator member 65 which projects into chamber 55 in alignment with the end of the fluted stem 54 of the poppet. The stem of the actuator is preferably provided with seal means such as the O-ring 66 and backup rings 67 and the actuator is normally urged by a biasing means, such as the coil spring 68, in a direction away from the fluted stem of the poppet (towards the right in FIGURE 1) to enable the poppet to normally close the passage 51.

Attached to the exterior of the plug 59 are a pair of trunnions 69 holding a removable pin 70 for pivotally supporting one end of a lever 71 having a camming surface 72 for operative engagement with the exteriorly projecting end of stem 64. Preferably, the lever 71 is locked in contact with the surface of the plug, as by means of a lockwire 73, and the cam surface is arranged so that upon angular rotation of the lever in a clockwise direction, as viewed in FIGURE 1, the actuator 65 will be moved towards the left into contact with the stem of the poppet 53 to open the passage 51. The lockwire 73 constitutes a safety device and must be out prior to utilization of the secondary hydraulic flow path; for example, in an hydraulic brake system, the lockwire 73 is cut prior to bleeding the brake system and is rewired after completion of the bleeding operation.

It will thus be observed that the provision of the instrumentalities contained within the auxiliary housing 12 establishes a secondary hydraulic path, parallel with the main path, from the inlet 13 of the fuse means to the outlet 14 whenever it is desired to circumvent the operation of the automatically controlled metering means in the main hydraulic path in order to allow an unrestricted or by-pass flow of fluid through the system, this secondary path including passage 20, annular chamber 16, passages 44, 51 and 45, annular chamber 17 and passage 23 to outlet 14.

Inasmuch as the present invention is subject to many modifications, variations and changes in details, it is intended that all matter contained in the foregoing description shall be interpreted as illustrative and not in a limited sense.

What is claimed is:

1. In a hydraulic fuse, the combination including housing means having inlet orifice means for connection with a source of fluid under pressure and outlet orifice means for connection with hydraulic load means, conduit means connected with the inlet and outlet orifice means, said conduit means including a main hydraulic path between said inlet and outlet orifice means and also including a parallel secondary hydraulic path between the inlet and outlet orifice means, said main hydraulic path including normally open metering valve means responsive to sustained flow of a predetermined volume of fluid from the inlet orifice means to the outlet orifice means when permitted by the existence of a lower pressure at the outlet means than at the inlet means to close said main hydraulic path and also responsive to the absence of a pressure differential in said main hydraulic path and to fluid pressure at said outlet orifice means in excess of pressure at the inlet orifice means to maintain at least a portion of the metering valve means open, said secondary hydraulic path including secondary valving means, and actuator means for opening said secondary valving means independently of the metering valve means to provide unrestricted flow of fluid through the secondary hydraulic path.

2. The invention as defined in claim 1, wherein said secondary valving means includes one-way check valve means and biasing said check valve means to a normally closed position.

3. The invention as defined in claim 2, wherein said secondary hydraulic path includes a passage in said housing, and said check valve means comprises a poppet valve having a stem slidable in said passage, and said actuator means includes means for operative engagement with the stem to open the poppet valve.

4. The invention as defined in claim 3, wherein said means for engagement with said stem includes pivotal camming means and manually operative means for rotating said camming means.

5. The invention as defined in claim 3, wherein said actuator means includes an element positioned in said housing for slidable movement in axial abutting engagement with said stem, and a lever pivotally mounted on said housing in camming engagement with said element.

6. The invention as defined in claim 1, wherein said housing includes an auxiliary housing, said secondary hydraulic path includes a passage in said auxiliary housing, and said secondary valving means includes a plurality of coacting elements, certain of said elements being removably received within axially aligned recessed portions of the auxiliary housing.

7. The invention as defined in claim 6, wherein said secondary valving means includes a slidably movable poppet valve having a stem for guiding said sliding movement, a retaining plug and spring means between the plug and poppet valve to urge movement in one direction, said secondary hydraulic path includes a passage provided within the auxiliary housing for slidably receiving the valve stem, and the auxiliary housing is provided with a recessed portion open to the exterior in alignment with the interior passage for removably receiving said plug.

8. The invention as defined in claim 6, wherein said secondary hydraulic path includes a chamber provided within said auxiliary housing and open to the exterior thereof, said secondary valving means includes a movable element having a portion thereof positioned in said chamber, and said actuator means includes plug means removably received in said chamber to close the chamber, said plug means including another element movably supported thereby for operative engagement with the movable element of the valving means.

9. The invention as defined in claim 8, wherein a coil spring is positioned within said chamber to urge said another element in one direction, and said plug means includes manually operable camming means mounted exteriorly thereof for operative engagement with said another element for movement thereof in the opposite direction.

10. The invention as defined in claim 1, wherein said secondary hydraulic path includes recess means provided in said housing open to the exterior, and said secondary valving means includes a plurality of elements movably supported in said recess means, said movable elements being removable from said chamber means, and removable plug means for closing said recess means and operatively positioning said elements within said recess means.

11. The invention as defined in claim 10, wherein said recess means is open to at least two spaced exterior surface portions of the housing, and a pair of plug means for closing said spaced surface portions, each of said plug 7 8 means being removably positioned for operative engage- 3,083,721 4/1963 Matthews et a1. 137599 X ment with a difierent one of said plurality of movable 3,217,731 11/1965 Swanson 137-599 X elements. 3,272,083 9/ 1963 Stoll 137--522 X References Cited FOREIGN PATENTS UNITED STATES PATENTS 5 470,445 4/ 1952 Italy.

2,138,125 11/ 1938 Schultz et al 137522 ROBERT G NILSON, Primary Examiner 2,306,903 12/1942 Ray 137522 X 2,592,486 4/1952 Stark 25116 2,772,065 11/1956 Thomas 251l6 10 25116, 251;137-384,523

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